County fights mosquitoes with aerial spraying

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The Santa Clara County Vector Control District sent a crew to fly out in a helicopter Thursday morning to cover 150 to 400 infested acres with mosquito control products to battle mosquitoes, according to a district source. They are expecting to see more hatching of eggs forcing them to might do another round, according to Acting District Manager Russ Parman.

A breakage a couple of weeks ago in the Palo Alto Baylands 640-acre tidal basin resulted in millions of dormant eggs hatching. These particular mosquitoes do not carry the West Nile Virus according to the San Jose Mercury News.

The SCCVCD used methoprene, an environmentally friendly chemical said to halt mosquito growth. The mosquitoes are able to fly up to a five-mile radius and access to the Baylands was restricted during the spraying but is now open to the public again read the SCCVCD website.

“A post-treatment survey is being done today and we should be looking at the full results by next Monday”, Parman stated in an email to The Paly Voice on Friday, “The effects of B.t.i.can be assessed fairly rapidly because it kills the larvae, but the methoprene does not produce immediate mortality. We’ll be collecting samples and bringing them back to the lab to see if the methoprene worked. As long as the water levels continue to rise and fall with the tides, we’ll probably be getting new eggs hatching continuously.”

Also adding that, “It’s likely that we’ll do at least one more treatment if we continue to see mosquito egg hatch in the floodbasin. That will probably occur late next week using an extended release methoprene granular formulation in an attempt to reduce the number of helicopter flights needed.”

These eggs can lay dormant for many years, even after repeated flooding, the SCCVCD’s official website said. High tides and seasonal rains, together with the short days and cooler temperatures of winter cause the eggs to hatch when they are submerged in water according to the SCCVCD.